I'm going to be getting foam injection insulation for my exterior walls to help with energy loss, and I was told I couldn't use this product in my ceilings. I live in the bottom two floors of a 5 story browstone condo, and my upstairs neighbors are very loud. I don't think there is any insulation of any kind between their floors (hardwood, of course) and my ceiling drywall. I was hoping I could spray some foam in there to deaden the sound a bit. The insulation installer recommended blown-in rockwool. He said it would require 2.5" holes to be cut at various places, but would not require the removal of the existing drywall. Should I go with his recommendation? Any solution that requires the removal of the ceiling drywall will likely be a no-go because of the cost.